Fundamental physical and chemical parameters reflect the operational status of diverse water/wastewater treatment processes including aerobic/anaerobic systems, coagulation/flocculation units and disinfection contact tanks. A holistic understanding of heterogeneity inside a given system is critical to optimize and troubleshoot operation under dynamic changing conditions. However, traditional sensors can only measure a single parameter at a single sampling point, and fail to profile the complete picture of operational status. Currently, wastewater treatment systems (e.g., aeration tanks, anaerobic digestors, anoxic tanks, storage tanks, pipelines) typically use conventional single-point sensing technology, which generally can only measure one parameter at a sampling site. This type of sensing generally can only obtain local information at a single point of wastewater treatment systems, which inhibits swift and efficient action under various upcoming events (e.g., wastewater quality/quantity, shocks) and can lead to low efficiency and malfunction of systems. In general, conventional probes/electrodes can only measure a single parameter at a single point, so that a broad spectrum of probes have to be installed in a waste facility (e.g., anaerobic digestor or “AD” system) to determine operational status, which can be extremely costly.
Although multi-meters (e.g., YSI® multi-meters) have been commercialized for measuring multiple parameters simultaneously, they are made by packing several probes in a single cartridge, meaning that they can only obtain readings at a single sampling point, and require a large space (FIGS. 1A and 1B). While multi-parameter meters (e.g., multiple probes packed into a single rigid cartridge) have improved monitoring, the single point limitations associated with the meters make it impossible to monitor dynamic waste streams in a heterogeneous system. In addition, multi-parameter meters are costly and generally have large space requirements. For example, a conventional cartridge hosting three (3) probes (e.g. temperature, pH, oxygen) is 1.5 m long and 0.5 m diameter for a permanent installation model, with a cost of S25,000-550,000 [Robert A. Linsenmeier and M. Yancey Charles, Improved fabrication of double-barreled recessed cathode O2 microelectrodes, Journal of applied physiology 63.6 (1987): 2554-2557]. For a system requiring the profile of multiple parameters at high temporal and spatial resolution, numerous multi-parameter meters are needed (e.g. 200-500 probes) with prohibitively high cost and space.
Micro-scale glass pipette electrodes have been developed to measure the chemical profiles inside biofilms and activated sludge flocs. These needle-shaped micro-electrodes are generally fabricated by either shielding a tapered metal wire with a glass micropipette or filling a glass micropipette with a low melting point alloy (e.g., platinum). However, the fragile glass pipette structure, time-consuming fabrication, and need for bulky micromanipulator to position micro-electrodes poses severe problems for field applications. Until now, glass pipette micro-electrodes have only been used in well-controlled lab-scale systems.
In the last decade, a micro-fabrication method—photolithography with chemical vapor deposition (PCVD) was developed for fabricating durable micro-scale electrical sensors to monitor water quality (e.g., metals, cyanide and formic acid). But PCVD process is complicated due to high temperature metal vapor (e.g., gold, platinum, etc.) deposition, photomask preparation, photoresist and etching. The strict fabrication condition (e.g., high temperature, dust-free and yellow filter requirement) limits selection of rigid sensor materials (e.g., silicon, silicon oxide) that is difficult for direct deployment in water/wastewater treatment systems. In addition, high cost photomask and metal deposition in PCVD protocols severely limits mass production of diverse types of electrical sensors.
A new fabrication method—inkjet printing technology (IPT) has gained high levels of interest due to three breakthroughs over PCVD. First, the IPT process only involves two steps: substrate material preparation and inkjet printer setup, which is much easier than PCVD process needing over 10 steps. Second, the IPT process can be easily conducted at room temperature and pressure, and thus greatly broadens the selection of sensor substrate materials (e.g., flexible thin polyimide film) that can be easily deployed in water/wastewater systems. Third, the cost of a sensor fabricated using the IPT process is only $0.20 (mainly the ink cost), about 1/150 of the cost using PCVD, which makes mass fabrication of miniature sensors feasible. IPT has been used to fabricate sensors for detecting hydrogen sulfide and humidity in the air and identifying cancer biomarker protein. However, there has been no report regarding IPT-fabricated sensors for water quality monitoring.
Thus, a need exists for improved sensor assemblies, and related methods of use. These and other inefficiencies and opportunities for improvement are addressed and/or overcome by the assemblies, systems and methods of the present disclosure.